Major Funding The Laura Moore Cunningham Foundation

Asteroids and Comets: Top 10 Questions

September 2015

Thanks to Brian Jackson, assistant professor of physics, Boise State University; and Camille Eddy, microgravity team leader, Boise State University for the answers.

1: How are asteroids formed?

Asteroids are formed from the leftover material after the sun and the planets formed. So they are collections of rock and dust that agglomerated, or formed into a mass, over millions of years ago. This occurred a long time ago, right at the birth of our solar system. (From Katrina at Liberty Elementary School in Boise)

2: How frequently do comets pass the Earth?

Comets enter the inner solar system every few months. Some years there are many comets entering in a single month. (From Ashley at Lewis and Clark Middle School in Meridian)

3: Has a comet ever hit our moon, and how many?

Comets impact the moon quite a bit. There are a lot of impact craters that you can see on the moon, and that happened from different meteorites, comets, and asteroids hitting the moon. (From Caden at Cynthia Mann Elementary School in Boise)

4: What was the first ever comet's name?

The first comet was called the Great Comet of 1680. It was also called Kirch's comet, and it was observed around 1680. Then it went away. However, we are still tracking it today. As of a couple of years ago, it was about 23 astronomical units (the distance between the Earth and the sun) away from the sun. (From Simran at Dalton Elementary School in Dalton Gardens)

5: What are inside asteroids?

The largest asteroids are actually big enough that they differentiate the interior. So, deep in the interior of these asteroids are iron and other metals. As you move to the exterior, you encounter more and more rock. Some of the smallest asteroids are actually low in gravity and full of holes. This means they have a very high porosity. Therefore, in some cases, asteroids are full of metal and rocks. In other cases, they are full of empty space. (From William at Eagle Elementary School in Eagle)

6: Can asteroids turn into comets?

Sometimes scientists have a hard time differentiating between what are comets and what are asteroids. This is because comets contain ice and asteroids do not. After many times around the sun, comets will start to lose their ice. Generally, comets don't turn into asteroids, but sometimes it is hard to tell the difference between the two. (From Colin at Cynthia Mann Elementary School in Boise)

7: Were dinosaurs wiped out when a huge comet or asteroid hit the Earth a long time ago?

In the beginning of 1980, planetary scientists and astronomers found ample (more than enough) evidence to suggest that the Earth received an impact about 65 million years ago on the Yucatan Peninsula in Mexico. The impact was so large that it actually enshrouded (surrounded) the entire Earth in a cloud of dust and blocked out the sun for many weeks or even months. This led to an environmental cataclysm (a large scale, violent event) that ultimately culminated in the extinction of dinosaurs. (From Mia at Dalton Elementary School in Dalton Gardens)

8: Is it possible to see asteroids and comets from Earth?

Sometimes it's hard to see asteroids and comets from Earth with the unaided eye, or without a telescope. However, the easiest part of a comet to see would be its tail when it's closer to Earth. (From Jerred at Cynthia Mann Elementary School in Boise)

9: Why do comets have tails?

Comets contain ice and when they get closer to the sun, they tend to stream out those particles. They expel the particles, and that's what we see in orbit. (From Austin at A. J. Winters Elementary School in Montpelier)

10: How big is the biggest comet?

Comet Sarabat has a core that is about 100 miles wide. Comet McNaught-Russell has a core that's around 15 miles long, but its tail is about 139 million miles long. (From Alex at Taylor's Crossing Public Charter School in Idaho Falls)

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